C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes
In the present work, the relationship between the large substituent effects on 3J(C1H) in 1-X-3-M-bicyclo[1.1.1]pentanes, I, and the polarizability of the bridgehead C3 - Mα bond is investigated. The existence of such a relationship is suggested by the finding that the effect of an electronegative s...
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todo:paper_01928651_v19_n2_p181_Giribet2023-10-03T15:09:07Z C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes Giribet, C.G. Ruiz De Azúa, M.C. Gómez, S.B. Botek, E.L. Contreras, R.H. Adcock, W. Della, E.W. Krstic, A.R. Lochert, I.J. Bicyclo[1.1.1]pentanes Bond polarizabilities CLOPPA-IPPP Localized orbitals NMR coupling constants In the present work, the relationship between the large substituent effects on 3J(C1H) in 1-X-3-M-bicyclo[1.1.1]pentanes, I, and the polarizability of the bridgehead C3 - Mα bond is investigated. The existence of such a relationship is suggested by the finding that the effect of an electronegative substituent X on 3J(C1Mα) couplings in I (M = H) is due to a distortion of the C3 - H bond toward the C1 center, which enhances the Fermi contact interaction. If such distortion originates in an electrostatic effect, then in other members of this series it can be expected that the substituent effects on 3J(C1 Mα) couplings should depend strongly on the C3 - Mα bond polarizability. Two approaches are followed. First, the ab initio CLOPPA-IPPP method is applied to study the C3 - Mα bond contribution to the molecular static polarizability tensor in I (M = H, F, CH3). Such bond polarizabilities are found to follow the same trend as calculated as well as experimentally determined substituent effects on 3J(C1Mα) couplings, which were measured as part of this work in I [X = H, Cl; M = F, CH3 and X = OCH3; M = Sn(CH3)3]. Second, 3J(C1Mα) couplings (M = H, CH3) are calculated at an ab initio level for X = H, F, and they are compared with those obtained in the parent compound (X = H) if the calculation is carried out in the presence of an inhomogeneous electric field. © 1998 John Wiley & Sons, Inc. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_01928651_v19_n2_p181_Giribet |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Bicyclo[1.1.1]pentanes Bond polarizabilities CLOPPA-IPPP Localized orbitals NMR coupling constants |
| spellingShingle |
Bicyclo[1.1.1]pentanes Bond polarizabilities CLOPPA-IPPP Localized orbitals NMR coupling constants Giribet, C.G. Ruiz De Azúa, M.C. Gómez, S.B. Botek, E.L. Contreras, R.H. Adcock, W. Della, E.W. Krstic, A.R. Lochert, I.J. C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes |
| topic_facet |
Bicyclo[1.1.1]pentanes Bond polarizabilities CLOPPA-IPPP Localized orbitals NMR coupling constants |
| description |
In the present work, the relationship between the large substituent effects on 3J(C1H) in 1-X-3-M-bicyclo[1.1.1]pentanes, I, and the polarizability of the bridgehead C3 - Mα bond is investigated. The existence of such a relationship is suggested by the finding that the effect of an electronegative substituent X on 3J(C1Mα) couplings in I (M = H) is due to a distortion of the C3 - H bond toward the C1 center, which enhances the Fermi contact interaction. If such distortion originates in an electrostatic effect, then in other members of this series it can be expected that the substituent effects on 3J(C1 Mα) couplings should depend strongly on the C3 - Mα bond polarizability. Two approaches are followed. First, the ab initio CLOPPA-IPPP method is applied to study the C3 - Mα bond contribution to the molecular static polarizability tensor in I (M = H, F, CH3). Such bond polarizabilities are found to follow the same trend as calculated as well as experimentally determined substituent effects on 3J(C1Mα) couplings, which were measured as part of this work in I [X = H, Cl; M = F, CH3 and X = OCH3; M = Sn(CH3)3]. Second, 3J(C1Mα) couplings (M = H, CH3) are calculated at an ab initio level for X = H, F, and they are compared with those obtained in the parent compound (X = H) if the calculation is carried out in the presence of an inhomogeneous electric field. © 1998 John Wiley & Sons, Inc. |
| format |
JOUR |
| author |
Giribet, C.G. Ruiz De Azúa, M.C. Gómez, S.B. Botek, E.L. Contreras, R.H. Adcock, W. Della, E.W. Krstic, A.R. Lochert, I.J. |
| author_facet |
Giribet, C.G. Ruiz De Azúa, M.C. Gómez, S.B. Botek, E.L. Contreras, R.H. Adcock, W. Della, E.W. Krstic, A.R. Lochert, I.J. |
| author_sort |
Giribet, C.G. |
| title |
C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes |
| title_short |
C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes |
| title_full |
C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes |
| title_fullStr |
C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes |
| title_full_unstemmed |
C3 - Mα bond contribution to polarizability tensor and 3J(C1Mα) NMR coupling constant in 1-X-3-M-bicyclo[1.1.1]pentanes |
| title_sort |
c3 - mα bond contribution to polarizability tensor and 3j(c1mα) nmr coupling constant in 1-x-3-m-bicyclo[1.1.1]pentanes |
| url |
http://hdl.handle.net/20.500.12110/paper_01928651_v19_n2_p181_Giribet |
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